I. Field of the Invention
This invention relates to electrical connectors of the modular type and specifically to such electrical connectors having more than one row of modules receivable in a modular housing or cell.
II. Description of the Prior Art
A typical multi-row modular electrical connector includes a housing or cell having a rectangular cross-section cavity or receiving area into which is receivable a plurality of rectangular cross-section modules each adapted to carry electrical contacts. The modules may, for example, be arranged into two rows, one overlying the other, between upper and lower housing or cell walls. Normally, the electrical contacts of each module are contained in through-bores between the upper and lower walls of the module. The modular upper and lower walls are spaced-apart a fixed distance and thus each module will typically have the same height. When stacked into two rows in the cell, the rows have a combined height of twice a module height. Hence, the cavity has a height between the inner surfaces of the upper and lower cell walls of twice a module height to snugly receive therebetween the two rows of modules.
The width of each module will vary, however, depending upon the number of contacts therein. As is well understood, a standard in the industry today is to place electrical contacts on approximately 0.1 inch centers. Thus, a two-contact module will have a width of approximately 0.2 inch (about 0.1 inch from contact center to contact center and about 0.05 inch between each contact center and the nearest outside edge of the module). Similarly, a module carrying five contacts will have a width of about 0.5 inch, ten contacts a width of about 1.0 inch, etc. Typically the modules are selected such that each row will have the same number of contacts, i.e., the same width.
By way of example, a modular connector may have twenty contacts carried by a total of three modules divided into a first row of two five contact modules and a second row of one ten contact module. Hence, each row will be approximately one inch wide. Also, to be compatible with the industry standard, the rows will each be about 0.1 inch in height and the cell cavity thus about 0.2 inch in height.
A wiring harness may be assembled with the foregoing exemplary connector by terminating a first set of five wires in five electrical contacts carried by the first module, terminating a second set of five wires in five electrical contacts carried by the second module and terminating a set of ten wires in ten electrical contacts carried by the third module. The three modules may then be inserted into the cell cavity, one at a time, to form the above-described two rows.
Once assembled, the modules would typically be held securely within the cell cavity by virtue of the tight friction fit between each module and the cell walls and the other modules. Also, to insure that the modules would remain in the cavity, the front of the cell would typically be provided with at least one rib extending between the upper and lower cell walls, and lips associated with each cell wall at the back thereof which would typically project into or toward the cavity. When the module is placed in the cavity, the front thereof would contact a rib and the back would contact the lips thereby wedging the module therebetween.
During assembly, the lips (and associated wall) would have to be urged from out of the cavity, i.e., out of path of the module, as the module entered the cell cavity and until the module was completely within the cavity (and contacting one of the forwarding ribs) whereupon the lip would snap back into place. As a result, the lips would likely be pressing tightly against the module wall during the entire traverse of the module as it entered the cell cavity. This tight press would make assembly very difficult. In the event of repair or the like, disassembly would also likely be very difficult for the same reason. Also, to remove a module would require urging the lips out of the path of the module and because the lips project into the cavity, it may be that some attempts to move the lips out of the way would result in damage to the cell and/or a module. Moreover, to first insert a module into the cell after one row is in place would require angling the module to wedge the lips outwardly making assembly more complicated.
In addition to the foregoing, repair or the like necessitating disassembly might typically result in a further problem, especially for the multi-row modular connector. This problem is one of mispositioning of modules during reassembly. For example, if the ten contact module of the previous exemplary connector were removed, the upper pair of five contact modules would be subject to falling away from the inner surface of the wall of the cell which they would otherwise be wedged against by the ten contact module. As a result, the modules may all fall lose from the cell leading to the possibility that the field technician might reinstall them in an incorrect position (e.g., the field technician may, for example, put the pair of five contact modules in the opposite order then that which was intended). This problem, of course, becomes more aggravated as the number of modules in each row increases. Accordingly, when the incorrectly reassembled connector is plugged into a mating connector, the electrical equipment involved will be wired incorrectly possibly leading to failure of, or damage to, the electrical equipment. Additionally, the dual row modular connector presents the assembly problem of keeping one row of modules in place before the second row is inserted.
Previously, in addition to the one dimensional securement provided by wedging (the module was restrained from movement fore and aft of the cell), multi-row modular connectors also provided a second dimension of securement to prevent lateral (left and right) shifting of a module. In the previous example, if one of the five contact modules were removed, the ten contact module would keep the other five contact module in its row thus making the first dimensional securement operative. To prevent lateral shifting, the modules might be provided with a rail on one wall thereof receivable in a slot in the cell walls. The rails, when so received, would prevent lateral shifting. Of course, such one and two-dimensional securement require restraint of movement in a third dimension (up or down, i.e., towards or away from a cell wall) to function. This third dimension of securing was provided by cooperation between modules of different rows. Hence, when the ten contact module is removed as described, the other modules may fall from the cell wall whereby the first and/or second dimensions of securing are no longer operative. The third dimension of securement is thus provided by other modules and the first and second dimensions of securement depend thereon as well. Because of this dependence on other modules, the aforementioned assembly and positioning difficulties and the like are present in the multi row modular connectors.